1. Field of the Invention
The present invention generally relates to an apparatus and method for driving and adjusting light, and more specifically to an apparatus and method for driving and adjusting light of a light-emitting diode (LED) lighting device, without the necessity to change the existing wiring or the structure of the lighting device, to change the lighting by using the apparatus and method for driving and adjusting light so that an LED driver has the light-adjustment capability and the lighting of the LED lighting device is adjustable.
2. The Prior Arts
As the environmental consciousness increases and the energy consumption awareness becomes an agenda, the LED lighting devices gain popularity because of the superior energy efficiency in comparison with the conventional incandescent lamps and fluorescent lighting devices. Therefore, LED is replacing the conventional incandescent or fluorescent bulbs in many lighting devices.
At present, the LED driver design focuses on how the LED driver keeps the LED in stable brightness when the input voltage changes. The advantages of this design approach include that (1) LED has a steady brightness, which does not flicker because of the change of unstable input voltage; (2) High efficiency; and (3) LED has steady color temperature. However, the disadvantage is that additional control signals are required for LED light adjustment; therefore, with the restrictions of the existing wiring, the structure of the lighting device and the light adjustment device, it is difficult to provide light adjustment for LED because this may imply re-wiring and purchase of new lighting device and light adjustment device. Therefore, the LED lighting device is still unable to replace the existing lighting devices.
The LED lighting device driven by AC directly is available, but the disadvantages include low efficiency, LED flickering because of current frequency, and high variation of LED color temperature. Also, because of being driven by AC directly, LED shows different color temperature at different voltage.
In addition, for the existing light adjusting apparatus, the light adjustment function is achieved by adjusting the power source voltage. However, the conventional fluorescent tube and energy-efficient bulb are not adjustable. In general, the following approaches are used for voltage adjustment. The first is to use a variable resistor to split the voltage. The second is to use a TRIAC or SCR to control the phase of the voltage conduction. However, when applied to the existing design for driving an LED, these approaches cannot achieve the object of light adjustment.
Hence, it remains an important issue in the LED driver design to replace the existing lighting with the LED without the necessity to change the existing wiring or the structure of the light device so that the LED light can be adjusted in addition to the lighting capability. In the mean time, how to maintain the steady brightness and avoid flickering caused by unstable input voltage, maintain high efficiency and low color temperature variation are also important issues to be solved.